Thomas varney



T. VARNEY QUARTZ MILL.

Patented Apr. 9, :1867.

m1 \N W @einen tatesiatwt Hite.

THOMAS vAnNnY, or ASAN rnaNoisoo, oALiFoRNiA.

- Leiters Patent No. 63,675, dated April i), 1867.

IMPOVEMBNT' 1N QUARTZ-MILLS.

TO WHOM IT MAY CONCERN:

Be it known that I, THOMAS VARNEY, of the city and county ot' San Francisco, and Stateof California,

have invented certain new and useful improvementsin Quartz-Grinders usedin pulverizing gold and silver ores, and for othertsimilar purposes; and l" do hereby declare that the following is a full, clear, and exact description of the' same, reference being had to the annexed drawings, making a part of this description, in which- Figure 1 is substantially a. vertical central section view ofa quartz-grinding machine-having my improvements.

Figure 24is a perspective view of the lower grinder; and

Figure 3 is a view from beneath ofthe lower or lgrinding faccef the upper grinder.

Similar letters of reference indicate corresponding parts in the different figures. (By mistake a different style of letter has been used in the drawings from that in the specification.)

The nature of my invention consists in. the use of two grinders with comparatively large diameter and small height, onestationary and the other revolved horizontally, their grinding faces being smooth and even, except so far as rendered otherwise by slots sunk;into'tlien1 up and down, and filled with wood or some equiva` lent substance, and so formed (the faces) that the space between them shall have and retain a. certain form, to wit, one that commences above with a thickness suliicient to admit the ore to be ground, and thence descends, at first, vertically, then gradually curving downward and outward, at. the same time gradnallydiminishing in thickness until at the lower and outer part it becomes nearly or quite horizontal, and the faces come nearly or quite in' contact with each other.

The bodyof the machine consists of the shell a, tig. l, resting upon the legs and bolted thereto through lugs on its periphery.' Through the bottom of this shell at one side is the discharge opening c. The vertical shaft d is steppedinto the box e in the ordinary manner, and is adjustcdvertically Aby means of the lighter bar j' and hand-wheel g. To the shaft d is keyed the driver, being a huh, h, with two arnis i. In the upper end of this hub is a hemispherical socket in which rests the correspondingly formed projection j of the centre piece c. To this centre piece is fastened by the bolts Z the revolving grinder m, on the under side of which are the lugs n, (shown by the dotted lines,) against which the arms of the driver press.Y Upon the top of the grinder m is placed the cap o. The stationary grinder p is fastened 'to the' shell aby the bolts o'. The upper end of the shaft d runs in the' box.3 in the arched cross-piece t, ,which-is bolted to the stationary grinder-p. This grinder extends sutliciently above the other to allow for wear, and to form a receptacle for the material to be ground The shaft is drvenby the gearing shown, or any of the ordinary methods. The grinders .are of hard cast iron or some other hard material. The form of the grinding Asurfaces is such that their lines in a vertical central section view, as in g. 1, are quart-er circles, tractor-y crvcs, or curves substantially like them-, so modified, however, as to produce the kind of opening between the grinding surfaces above indicated, to wit, one commencing at the top of a size sutiicient to admit the material to be groundgand thence gradually diminishing as it extends downward and outward until' at the periphery the grinding faces come in contact with each other, or nearly so. The advantage of this kind of opening is that it receives the material to be ground coarse, and graduallyreduccs it and'discharges it as n'e as desired by a single passage between the grinders without the'eXpcndit-ure ofthe time and power involved in the ordinary pan method. But itis absolutely necessary that this opening should retain its form as above described, and as the method of securing this' constitutes one of-the claims I make, I will describe it particularly.A

All grinding machines heretofore used having grinding faces of thesame general form as mine have been Constructed on substantially the tractory-conoidal principle, that istto say, the grinding surfaces have had the form described by the revolution of the tractory curvo about the line of traction. The chief characteristic of such surfaces is that when fed at all parts with like material, and while the space between the grinding surfaces is of the same thickness throughout, the faces retain their original form; but if the openingbe enlarged above so as .to allow the feed to enter coarse and become finer as it descends, the comparative wear above is less than below, so that the wedgeshaped opening between the grinders 'gradually disappears till the faces of the grinders come in contact with each othcrthroughout their entire faces, and tho feed and work done grow less and less, and at last almost entirely cease. To prevent this r'esu'lt it is necessary to cause an increased wear above. This I accomplish by expanding, as it were, the old form horizontally, that is to say, while the curve ot' the faces upand down romains the saine, the diameters of the grinders are increased. l This increas'esthe velocity of the upper morcthan it does the lower parts, 'and eonscque-ptly increases the wear above more than that below. In other words, with grinding faces having .their vertical sections ofthe form above described, and a fixed or constant height, if we bring theirupper parts to a pointat the centre oi' motion, these upper parts, having no motion, will not grind at all, while the parts below will have a velocity and grz-nling capacity' in pro portion to their distances from 'the centre of motion. This is one. extreme, New if we expand the grinding surfaces horizontally infinitely, (leaving their height and vertical form the sanie the upper will have the same velocity as their lower parts. This is the other extreme. Between these extremes wel select the inean suited to our purpose. Starting from the first-named extreme, by'expandlng the grinders horizontally untilA their base is four times their height, the wear will be substantially like that of grinders constructed on the tractory principle, in which thc grinding surfaces when cquidistant from eachother at all points,jand when fed at all points with like material, wearin proportion at all points and' preserve their original form. But with I this relative diameter and height, if we should make the wedging opening between the grinders and feed with coarse material, the result would be that the lower parts would wear faster than the upper ones, and the opening would soon disappear. To obviate this we have only to continue the expansion. until the velocity above efempared with' that below is suilicicnt tto-cause wear above to suchv a degree coinparcd with that bclow'as to'plcserve the opening required. It will be .apparent that the larger the opening is at the top, the greater the diam eter should be compared'withrthe. height in order to preserve Athat opening. For grinding iine material like ordinary sand, (when theopcn'ing required above is slight,) the opening will be preserved by having the diameter but slightly in excess of four/times the height; but for grinding material of vthe size of wheat, the diameter should bc at least tive times they height, and'frorr every-increase in the sizc ofthe material there should be a corresponding increase .of diameter. The grinders are made with increasing thickness from the'upper edge to the periphery, thus making the thickness of caclrpart in`proportiou to its wear, so that-when worn out nothing remains to throw away but a"..l:hin` shell of uniform thickness. lf desired, cach grinder 'nay be composed of a shell with 'shoes fastened therctofthe shoes occupying thc spaces between thc'wooden slots. This arrangement allovrstlic shell to housed permanently, and the shoes to be' removed andrenewed at pleasure. Thiais the proper style for large inills. Upand down, the faces of the grinders, at short distances .from each other, are'sunkiuto the grinders,- nnd nearly throughthcm, slots or channels which are filled with hard wood w driven Ain endwise and cut off ilush with the face, leaving the face when new perfectly smooth and even.. These chaunels for the wood may be at r'ight angles 4to'fthc'line of motionA lor varied therefrom. By making them so that while in rution thc upper ends shall bc 4in advance of thc lower, the discharge will be facilitated. It is not indispensable that the wood should-,in all casters extend `to the top of thelgrinding faces. From the top, part way ldown,'corrugations may be substituted, but thc lower parts of the 'aces should be made as described.

Thcfoperation is as follows: On setting the shaft in motion thearins of the driver press against thcilugs n,

on the lower .side ofthe lower grinder and, revolve it. Thcjoint between the projection j and hub h allows the faces of the grinders to adjust themselves to cach other Instead of this joint the lowcrgrinder muy be attached rigidly to the sha-ft, if desired. l The speed should be considerable, sufficient to causo a proper discharge. With a slow movement and the faces ofthe grinders set' for iinc work, the ore will pass through very slowly. Centrifugal force must bo mainlydepend'edupou for a {Xi-ener discharge. p The ere may be introduced by any of the ordinary methods for hopper feeding,l and should be accompanied by a constant stream of water of a size suicien t, at least, to produce an amalgamating pulp. Iuilnediatcly on entering between the grinders the ore becomes distributed, the .course remaining above and'the tine going further down uccording'to its fineness. The wood being dressed by their own operation.

sorter, keeps wnrh'slightly-.iu advance of the iron, leaving a shallow'groovo along the face of the wood, down which ore passes of larger size than could otherwise penetrate the same distance downward. The ore in these grooves is held up by t/he wood of thc lower, and down by the wood of the upper grinder, sa as to bc caught by the opposite lronlsurface 'and further reduced, the grooves servingas feeders to thc iron surfaces. The greatest wear takes-.place on on'e sideof the wood, from whence it'(the wear) diminishes gradually to the opposite side, where the woedremains flush with the iron face. Thcsidc least worn is the one first reached by the orc in its horizontai movement. Another 'pcbuliarity'of this worn' groove is that it is comparatively deep at the upper end, and lgradually diminishes indepth as it descends, until near and at the periphery it totally disappears, or very nearly so,u

leaving tho grinding faces there smooth and even, thus effectue-,ily preventing the escapo of the orcnntil it is'v reduced to the fineness desired. The rule seems to be that the size of the groove on any given line about the faces of the grinders will be in proportion to the size of the ore on that line, which itself depends'upon the distance ofthe grinders from each other on said line. y

From the foregoing it will be apparent that the form of thc opening between the grinders, as well as that of the grooves-along the wood, is self-preserving; that the faces ofthe grinders are, as it were, kept constantly Havingthus described myinvention, what I claim as new, and desire.to secure by Letters Patent, is-

The combination of the lslots in the smoothY grinding surfaces filled with wood, with the peculiar form of the revolving grinder m, and stationary grinder p, whcnconstructcd und operating substantially as described. and

for the purpose `as set forth.I y

THOMAS VARNEY.

Witnesses:

ALFRED Bix, Cuantas W. Cnocnsn. 

